In recent years, systems for retrieving and providing an optimum solution to an inquiry from a user have been studied eagerly. Furthermore, in connection with development of such systems, technologies of natural language processing and artificial intelligence have been studied in order to analyze the syntax and the meaning of the inquiry entered by the user or to retrieve a solution to the inquiry.
For example, a question answering system has been proposed that outputs a candidate answer evaluated as the optimum to a question (refer to US patent application publication No. US 2015/0026106 A1). This question answering system retrieves candidate answers to a question, calculates a score representing the extent that the candidate answer is right to the question using a learning function for each of the combinations of a question and a candidate answer, and outputs the candidate answer which is most likely to be a right answer based on the calculated scores.
In the meanwhile, a requested matter identification system that analyzes an input sentence of a user's request described in natural language, determines whether the requested matter in the input sentence matches any of the predefined requests, and identifies and outputs the requested matter in the input sentence (refer to US patent application publication No. US 2009/0099840 A1).